dwh_tutorial

12. METADATA CONCEPTS
DWH
What is Metadata?
Metadata is simply defined as data about data. The data that is used to
represent other data is known as metadata. For example, the index of a book
serves as a metadata for the contents in the book. In other words, we can say
that metadata is the summarized data that leads us to detailed data. In terms of
data warehouse, we can define metadata as follows:
Metadata is the roadmap to a data warehouse.
Metadata in a data warehouse defines the warehouse objects.
Metadata acts as a directory. This directory helps the decision support
system to locate the contents of a data warehouse.
Note: In a data warehouse, we create metadata for the data names and
definitions of a given data warehouse. Along with this metadata, additional
metadata is also created for time-stamping any extracted data, the source of
extracted data.
Categories of Metadata
Metadata can be broadly categorized into three categories:
Business Metadata - It has the data ownership information, business
definition, and changing policies.
Technical Metadata - It includes database system names, table and
column names and sizes, data types and allowed values. Technical
metadata also includes structural information such as primary and foreign
key attributes and indices.
Operational Metadata - It includes currency of data and data lineage.
Currency of data means whether the data is active, archived, or purged.
Lineage of data means the history of data migrated and transformation
applied on it.
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